Method of manufacturing a carcass structure and a vehicle tire

ABSTRACT

A method of manufacturing a carcass structure for vehicle tires includes preparing strip sections, each comprising longitudinal and parallel thread elements coated at least partly with at least one layer of raw elastomer material. A first series of strip sections is laid down onto a toroidal support. First primary portions of annular reinforcing structures are applied against end flaps of the first series strip sections. At least one second series of strip sections is laid down onto the toroidal support. Together, the first and second series define a first carcass ply. A third series of strip sections is laid down onto the toroidal support. Second primary portions of the annular reinforcing structures are applied against end flaps of the third series strip sections. At least one fourth series of strip sections is laid down onto the toroidal support. Together, the third and fourth series define a second carcass ply.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/EP99/07962, filed Oct. 20, 1999, in the European Patent Office;additionally, Applicants claim the right of priority under 35 U.S.C.§119(a)-(d) based on patent application No. 98830662.7, filed Oct. 30,1998, in the European Patent Office; further, Applicants claim thebenefit under 35 U.S.C. §119(e) based on prior-filed, now abandonedprovisional application No. 60/114,158, filed Dec. 29, 1998, in the U.S.Patent and Trademark Office; the contents of all of which are reliedupon and incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a method of manufacturing a carcassstructure for tires for vehicle wheels.

The invention also relates to a carcass structure for tires for vehiclewheels obtainable by the above method, said carcass structurecomprising; at least one carcass ply formed of strip-like sections eachof which extends in a substantially U-shaped conformation following thecross-section outline of the tire and comprises one or more thread-likeelements longitudinally arranged parallelly of each other and preferablyat least partly coated with a layer of raw elastomer material; and apair of annular reinforcing structures each engaged close to arespective inner circumferential edge of the carcass ply.

DESCRIPTION OF THE RELATED ART

Manufacture of tires for vehicle wheels involves formation of a carcassstructure essentially made up of one or more carcass plies substantiallyhaving a toroidal conformation and presenting their axially oppositeside edges engaged to respective annular, circumferentiallyinextensible, reinforcing elements usually referred to as “bead cores”.

Applied to the carcass structure, at a circumferentially outer position,is a belt structure comprising one or more belt strips having the shapeof a closed ring, which are essentially made up of textile or metalcords suitably oriented relative to each other and to the cordsbelonging to the adjacent carcass plies.

Then, at a circumferentially outer position of the belt structure atread band is applied which usually consists of a strip of elastomermaterial of suitable thickness.

It is to point out that, to the aims of the present description, by theterm “elastomer material” it is intended a rubber blend in its entirety,i.e. the assembly formed of a base polymer suitably amalgamated withmineral fillers and/or process additives of various types.

Ultimately, a pair of sidewalls is applied to the opposite sides of atire being manufactured, each of said sidewalls covering a side portionof the tire included between a so-called shoulder region, arranged closeto the corresponding side edge of the tread band, and a so-called beadarranged at the corresponding bead core.

The traditional production methods essentially provide that the abovelisted tire components should be first made separately of each other, tobe then assembled during a manufacturing step of the tire.

For example, for making the carcass ply or plies to be associated withthe bead cores in order to form the carcass structure, it is firstrequired that, by an extrusion and/or calendering process, a rubberizedfabric comprising longitudinally-disposed continuous textile or metalcords should be produced. This rubberized fabric is submitted to atransverse cutting operation to produce sections of predeterminedlengths that are subsequently joined together so as to give origin to acontinuous ribbon-like semifinished product, havingtransversely-arranged parallel cords.

This manufactured article must then be cut into sections the length ofwhich is correlated with the circumferential extension of the carcass tobe produced.

Manufacturing methods have been also proposed in which, instead ofresorting to production of semifinished articles, the carcass structureis made directly during the tire manufacturing steps.

For example, U.S. Pat. No. 5,453,140 herein referred to as an example ofthe most pertinent state of the art, discloses a method and an apparatusforming a carcass ply starting from a single cord that has beenpreviously wound up on a reel.

In accordance with the method and apparatus described in the abovepatent, at each working cycle of the apparatus the cord taken up fromthe reel by power-driven pulling rollers and maintained taut by apneumatic tensioning system is cut to size so as to obtain a section ofa predetermined length.

The cord section is taken up by a grip element mounted on a belt loopedaround power-driven pulleys to be transversely laid down on the outersurface of a toroidal support.

The section ends are then engaged by folding members of the belt typeoperating on opposite sides of the toroidal support to radially applythe cord section to the toroidal support itself by slider elementsacting like fingers along the section side portions.

Repetition of the above described working cycle leads to deposition ofthese cord sections in a circumferential side-by-side relationship untilthe whole circumferential extension of the toroidal support is covered.

Necessarily, the toroidal support is previously coated with one or moreraw rubber layers having a dual function, that of adhering to the cordslaid down thereon so as to conveniently hold them in a fixedpositioning, and that of forming an inner air-proof layer in thefinished tire.

Tires obtained by this manufacturing method have a carcass structure inwhich the carcass ply or plies are formed of individual cords eachhaving two side portions axially spaced apart from each other andradially oriented relative to the rotation axis of the tire, and a crownportion extending at a radially outer position between the sideportions.

Within the scope of the carcass structure manufacture, it is also knownthat close to each of the tire beads, the opposite ends of theindividual cords forming a carcass ply are arranged in an alternatingsequence, at axially opposite positions relative to an annular anchoringelement forming said bead core, having the shape of a crown made up ofradially-overlapping thread or wire coils, as can be viewed from PatentEP 0 664 231 and U.S. Pat. No. 5,702,548.

In the above mentioned art all cords forming the carcass ply or plieshowever, are substantially arranged in the neutral axis of resistance tobending of the respective bead. Under this circumstance, the structuralresistance of the beads must necessarily rely on the stiffness of thefilling inserts of very hard elastomer material incorporated into thebead structure, the behaviour of which feels the effects of temperaturechanges due both to environmental factors and to stresses producedduring normal operation.

In Patent FR 384 231 it is proposed to make a carcass structure bydeposition on a toroidal support, of a series of rectangular small bandsof rubberized fabric disposed circumferentially in side-by-siderelationship and arranged in radial planes relative to the geometricaxis of the support drum itself. Deposition of the small bands iscarried out in such a manner that the end flaps of two non-consecutivesmall bands are partly covered with the end flaps of the small bandinterposed therebetween. Spaces existing between the end flaps of thecovered small bands are filled with trapezoidal inserts applied to theend flaps of the small band placed in overlapping relationship thereon.Deposition of the small bands is executed in different overlappedlayers, the number of which is correlated with the thickness to be givento the carcass structure. The presence of said trapezoidal inserts givesrise to thickening of the carcass structure at the bead regions, whereit has a thickness which is twice that found at the crown.

In U.S. Pat. No. 4,248,287 it is disclosed a method according to whichformation of the carcass structure involves that a plurality of layerseach formed of radial strips consisting of rubberized threads andcircumferentially disposed in side by side relationship should be laiddown on a toroidal drum. When deposition has been completed, at the beadregion two bead cores are applied and the end flaps of the carcasslayers formed by the radial strips are then turned back around them.

The Applicant has found that important advantages can be achieved, bothin terms of simplification of the production processes and in terms ofimprovement of the behavioural features of the tire, if the carcass plyor plies are manufactured by conveniently laying down strip-likesections, each comprising a plurality of cords parallel to each otherincorporated into an elastomer layer, onto a rigid toroidal support.

In this connection the Applicant has already developed severalmanufacturing methods being the object of respective European patentapplications.

For instance, in European patent applications No. 97830731.2 and No.97830733.8 a manufacturing method and a tire are respectively describedin which the carcass structure is obtained by making a first and asecond carcass plies each accomplished by strip-like sections laid downsequentially in a circumferential side-by-side relationship.

Tires obtained as described in these patent applications have the endportions of the strip-like sections belonging to the first and secondcarcass plies disposed on respectively opposite sides relative to theannular reinforcing structures of the beads.

This expedient, in combination with the respectively crossed orientationof the strip-like sections belonging to one and the other carcass plies,offers important advantages in terms of structural resistance of thetire close to the beads and the sidewalls.

In the European patent application No. 98830472.1, in the name of thesame Applicant as well, accomplishment of a carcass ply is proposedwhich is carried out by depositing a first and a second series ofstrip-like sections in alternated sequence, in which the sectionsbelonging to the first and second series terminate at respectivelyopposite sides relative to the reinforcing structures of the beads.

Advantages can be thus achieved in terms of structural resistance at thetire beads and sidewalls even in the presence of a single carcass ply.

SUMMARY OF THE INVENTION

In accordance with the present invention, it has been found that, forachieving exceptional qualities of mechanical resistance to stressesinduced in the acceleration and deceleration steps, as well as in acondition of slip running, it is convenient that two carcass pliesshould be arranged which are each formed of two series of strip-likesections laid down in an alternated sequence, the sections of each plyterminating at respectively opposite sides of a respective portion ofthe reinforcing structure at the bead.

In particular, it is an object of the invention to provide a method ofmanufacturing a carcass structure for motor-vehicle tires, characterizedin that it comprises the steps of: preparing strip-like sections eachcomprising longitudinal and parallel thread-like elements coated atleast partly with at least one layer of raw elastomer material; layingdown a first series of said strip-like sections onto a toroidal support,each of them extending in a substantially U-shaped configuration aroundthe cross-section outline of the toroidal support itself andcircumferentially distributed according to a circumferential pitchcorresponding to a multiple of the strip-like section width; applyingfirst primary portions of annular reinforcing structures against endflaps of said strip-like sections belonging to the first series, ataxially opposite positions relative to an equatorial plane of thesupport drum; laying down on the toroidal support, at least one secondseries of said strip-like sections each extending according to aU-shaped conformation around the cross-section outline of the toroidalsupport, between two consecutive sections of the first series, in orderto define a first carcass ply together with said last-mentionedsections, each of the sections of the second series having end flapsoverlapping the respective primary portions of the annular reinforcingstructures at an axially opposite position relative to the end flaps ofthe sections of the first series; laying down on the toroidal support, athird series of said strip-like sections each extending according to asubstantially U-shaped conformation around the cross-section outline ofthe toroidal support itself and circumferentially distributed accordingto a circumferential pitch corresponding to a multiple of the strip-likesection width; applying second primary portions of said annularreinforcing structures against the end flaps of said strip-like sectionsbelonging to the third series, at axially opposite positions relative tothe first primary portions; laying down on the toroidal support, atleast one fourth series of said strip-like sections each extendingaccording to a U-shaped conformation around the cross-section outline ofthe toroidal support, between two consecutive sections of the thirdseries, in order to define, together with said last-mentioned sections,a second carcass ply overlapping the first carcass-ply, each of thesections of the fourth series having end flaps overlapping therespective second primary portions of the annular reinforcing structuresat an axially opposite position relative to the end flaps of thesections of the third series.

In more detail, the strip-like sections making up the first and secondcarcass plies respectively, are provided to be laid down in arespectively crossed orientation, preferably in an orientation inclinedat an angle included between 15° and 35° relative to a circumferentialextension direction of the toroidal support.

According to a preferential embodiment of the invention, also carriedout is the step of applying additional portions of the annularreinforcing structures against the end flaps of the strip-like sectionsbelonging to the fourth series, so that each of said end flaps isenclosed between the second primary portion and the additional portionof the respective annular reinforcing structure.

Advantageously, each of said strip-like sections is laid down so as toform two side portions substantially extending in the direction of thegeometric rotation axis of the toroidal support at mutually spaced apartpositions in an axial direction, and a crown portion extending at aradially outer position between the side portions, the crown portions ofthe strip-like sections belonging to the first and second carcass pliesrespectively being disposed consecutively in side by side relationshipalong the circumferential extension of the toroidal support.

In more detail, the side portions of said strip-like sections are maderadially converge towards the geometric rotation axis of the toroidalsupport.

It is also provided that the side portions of each strip-like sectionbelonging to the first series and the third series respectively shouldbe each partly covered with a side portion of at least onecircumferentially consecutive section belonging to the second series andthe fourth series respectively, at a stretch included between a radiallyouter edge of the respective primary portion of the annular reinforcingstructure and a transition region between said side portions and crownportions.

In accordance with a further aspect of the invention, to be also adoptedindependently of that which has been previously pointed out,accomplishment of at least one of said first and second primary portionsof each annular reinforcing structure comprises the steps of: layingdown at least one elongated element in concentric coils to form acircumferentially inextensible annular insert substantially in the formof a crown; forming at least one filling body of raw elastomer material;joining the filling body to the first circumferentially inextensibleannular insert.

Preferably, said elongated element is deposited directly against the endflaps of the strip-like sections previously deposited on the toroidalsupport, to form said first annular insert directly in contact with thestrip-like sections themselves.

According to a possible preferential solution, said filling body isformed by depositing a continuous strip of elastomer material directlyagainst the annular insert previously applied to the end flaps Of thestrip-like sections previously laid-down.

Alternatively, the elongated element is laid down in a forming seatdefined in a moulding cavity in which the filling body is subsequentlyformed, so that joining of said filling body to the annular insert iscarried out concurrently with formation of the filling body itself.

In more detail, said joining step can be carried out by applying thefilling body against said annular insert previously applied to the endflaps of the strip-like sections laid down on the toroidal support.

Preferably, formation of said additional portion of each annularreinforcing structure comprises the step of depositing at least oneelongated element in concentric coils to form an additionalcircumferentially inextensible annular insert substantially in the formof a crown.

In more detail, said elongated element is preferentially laid downdirectly against the carcass structure during the formation step on thetoroidal support.

It is a further object of the invention to provide a carcass structurefor vehicle wheel tires, characterized in that said first carcass plycomprises: a first and a second series of strip-like sections arrangedin a mutually alternating sequence along the circumferential extensionof the carcass structure, said second carcass ply comprises a third anda fourth series of strip-like sections arranged in a mutuallyalternating sequence along the circumferential extension of the carcassstructure, each of said annular reinforcing structures comprising atleast: one first primary portion having an axially inner side turnedtowards end flaps of the sections belonging to the first series and anaxially outer side turned towards end flaps of the sections belonging tothe second series, and one second primary portion having an axiallyinner side turned towards end flaps of the sections belonging to thethird series and an axially outer side turned towards end flaps of thesections belonging to the fourth series.

In more detail, sections of the first and second series extend in acrossed orientation with respect to the strip-like sections of the thirdand fourth series, preferably at an angle included between 15° and 35°relative to a circumferential-extension direction.

It is preferably provided that each of said annular reinforcingstructures further comprises at least one additional portion disposedagainst the end flaps of the strip-like sections belonging to the fourthseries, on the opposite side relative to the second primary portion ofthe annular structure itself.

Advantageously, each of said strip-like sections has two side portionssubstantially extending towards a geometric axis of said carcassstructure at mutually spaced apart positions in an axial direction, anda crown portion extending at a radially outer position between the sideportions, the crown portions belonging to the sections of the first andsecond series respectively, and of the third and fourth seriesrespectively, being arranged in mutual side by side relationship alongthe circumferential extension of the carcass structure.

It is provided that the side portions of said strip-like sectionsradially converge towards a geometric rotation axis of the carcassstructure.

In more detail, the side portions of each strip-like section belongingto the first and the third series respectively should be each partlycovered with a side portion of at least one adjacent strip-like sectionbelonging to the second and fourth series respectively, at a stretchincluded between a radially outer edge of the respective primary portionof the annular reinforcing structure and a transition region betweensaid side portions and crown portions.

Advantageously, the individual strip-like sections belonging to one ofsaid series respectively, are disposed according to a circumferentialdistribution pitch corresponding to a multiple of the width of thestrip-like sections themselves.

Preferably, the strip-like sections each have a width included between 3and 15 mm, and each of them comprises three to eight thread-likeelements.

It is also preferably provided that said thread-like elements should bedisposed in the respective strip-like sections according to a mutualdistance between centres not lower than 1.5 times the diameter of thethread-like elements themselves.

In accordance with a further independent aspect of the invention, eachof said first and second primary portions of each of said inextensibleannular structures comprises: a circumferentially inextensible annularinsert substantially in the form of a crown disposed coaxially with thecarcass structure and close to an inner circumferential edge of thecarcass plies, said annular insert being made up of at least oneelongated element extending in concentric coils; a filling body ofelastomer material having one side joined to the annular anchoringinsert.

Preferably, each of said annular reinforcing structures furthercomprises at least one additional portion disposed against the end flapsof the strip-like sections belonging to the fourth series, on theopposite side relative to the second primary portion of the annularstructure itself.

Advantageously, said additional portion comprises an additionalcircumferentially-inextensible annular insert substantially in the formof a crown, made up of at least one elongated element extending inconcentric coils and disposed coaxially with the carcass structure at aposition axially close to the filling body of the second primary portionof the respective inextensible annular structure. Preferably, thefilling body of elastomer material of each of said primary portions hasa hardness included between 48° and 55° Shore D at 23° C.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages will become more apparent from thedetailed description of a preferred, non-exclusive embodiment of amethod of manufacturing a carcass structure for tires for vehiclewheels, and a carcass structure obtainable by said method, in accordancewith the present invention. This description will be taken hereinafterwith reference to the accompanying drawings, given by way ofnon-limiting example, in which:

FIG. 1 is a fragmentary split perspective view of a tire provided with acarcass structure manufactured in accordance with the present invention;

FIG. 2 is a diagram showing accomplishment of a continuous strip-likeelement intended for formation of the carcass ply or plies;

FIG. 3 is a cross-section of an embodiment of said strip-like element;

FIG. 4 is a fragmentary perspective view diagrammatically showing thedeposition sequence of a first series of strip-like sections forformation of a first tire carcass ply in accordance with the invention;

FIG. 5 is a fragmentary diametrical section view of a portion of aninextensible annular structure, to be inserted at the tire bead, duringa moulding step for manufacturing the same;

FIG. 6 is a fragmentary perspective view of a first primary portion ofthe inextensible annular structure axially applied against the sideflaps of the strip-like sections belonging to the first series andpartly covered with the end flaps of strip-like sections belonging to asecond series;

FIG. 7 shows a second primary portion of the annular reinforcingstructure applied to the end flaps of a third series of strip-likesections previously laid down onto the first carcass ply;

FIG. 8 shows an additional portion of the annular reinforcing structureapplied to the end flaps of a fourth series of strip-like sectionsalternated with the strip-like sections of the third series;

FIG. 9 diagrammatically shows application of said additional portion tothe carcass structure, partly seen in cross-section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the drawings, a tire for vehicle wheels having acarcass structure 2 manufactured by a method in accordance with theinvention has been generally identified by reference numeral 1.

The carcass structure 2 has a first carcass ply and a second carcass ply3 a, 3 b substantially shaped in a toroidal conformation and engaged, bytheir opposite circumferential edges, with a pair of annular reinforcingstructures 4 (only one of which is shown in the drawings), each ofwhich, when the tire has been finished, is located at the region usuallyidentified by the name of “bead”.

Applied to the carcass structure 2, at a circumferentially outerposition, is a belt structure 5 comprising one or more belt strips 6 a,6 b and 7. Circumferentially overlapping the belt structure 5 is a treadband 8 in which, following a moulding operation carried out concurrentlywith the tire vulcanization, longitudinal and transverse hollows 8 aarranged to define a desired “tread pattern” have been formed.

Tire 1 further comprises a pair of so-called “sidewalls” 9 laterallyapplied to the carcass structure 2 on opposite sides thereof.

The carcass structure 2 can be possibly coated on its inner walls with aso-called “liner” 10, essentially consisting of a layer of an air-proofelastomer material adapted to ensure a tight seal of the tire itselfwhen inflated.

Assembling of the above listed components, as well as production of oneor more of same, takes place with the aid of a toroidal support 11,diagrammatically shown in FIG. 9, having a shape matching that of theinner walls of the tire to be made.

The toroidal support 11 can have reduced sizes relative to those of thefinished tire, according to a linear measure preferably included between2% and 5%, taken just as an indication along the circumferentialextension of said support at the equatorial plane X—X thereof,coinciding with the equatorial plane of the tire itself.

The toroidal support 11, not described or illustrated in detail as it isnot particularly important to the aims of the invention, can be forexample made up of a collapsible drum or an inflatable chamber suitablyreinforced for taking and keeping the desired toroidal conformation inan inflated condition.

After the above statements, manufacturing of tire 1 first involvesformation of the carcass structure 2, beginning with the possibleformation of liner 10.

This liner 10 can be advantageously made by circumferentially winding uparound the toroidal support 11, at least one ribbon-like small band 12of an air-proof elastomer material, produced by an extruder and/or acalender placed close to the toroidal support itself. As can be inferredfrom FIG. 1, winding of the ribbon-like small band 12 substantiallytakes place in circumferential coils disposed consecutively in side byside relationship so as to follow the cross-section outline of the outersurface of the toroidal support 11.

To the purposes of the present invention, by cross-section outline it isintended the configuration exhibited by the half-section of the toroidalsupport 11 sectioned in a plane radial to its own geometric rotationaxis, not shown in the drawings, coinciding with the geometric rotationaxis of the tire and, consequently, of the carcass structure 2 beingmanufactured.

In accordance with the present invention, the first carcass ply 3 a isdirectly formed on the toroidal support 11 by, as better clarified inthe following, laying down a first and a second series of strip-likesections 13, 14 formed of at least one continuous strip-like element 2 apreferably having a width included between 3 mm and 15 mm.

The second carcass ply 3 b is in turn formed in superposed relationshipwith the first carcass ply 3 a by, as better clarified in the following,laying down a third and a fourth series of strip-like sections 15, 16that can be made out of said continuous strip-like element 2 a as well.

As viewed from FIG. 2, preparation of the continuous strip-like element2 a essentially involves that one or more thread-like elements 17, andpreferably three to ten thread-like elements 17, fed from respectivereels 17 a, should be guided through a first extruder 18 associated witha first extrusion apparatus 19 supplying raw elastomer material throughthe extruder itself.

It is pointed out that, to the purposes of the present description, by“extruder” it is intended the extrusion apparatus portion alsoidentified in the art as “extrusion head”, provided with a so-called“die” passed through by the product being worked at a shaped outlet portconveniently sized for meeting the geometric and dimensional features tobe given to the product itself.

The elastomer material and thread-like elements 17 are intimately joinedwithin the extruder 18, giving rise at the extruder outlet to thecontinuous strip-like element 2 a formed of at least one layer ofelastomer material 20 in the thickness of which the thread-like elementsthemselves are incorporated.

Depending on requirements, guiding of the thread-like elements 17 inextruder 18 can take place in such a manner that they are not integrallyincorporated into the elastomer material layer 20 but appear on one orboth of the surfaces thereof.

The thread-like elements 17 can be each made, for example, either of atextile cord preferably of a diameter included between 0.6 mm and 1.2mm, or of a metallic cord preferably of a diameter included between 0.3and 2.7 mm.

Advantageously, if required, the thread-like elements 17 can be disposedin the continuous strip-like element 2 a in such a manner that they givethe obtained carcass ply 3 unexpected qualities of compactness andhomogeneity. To this purpose, the thread-like elements 17 can bedisposed for example according to a thickness greater than sixthread-like elements per centimetre, circumferentially measured on thecarcass ply 3 close to the equatorial plane X—X of tire 1. In any caseit is preferably provided that the thread-like elements 17 should bedisposed in the strip-like element 2 a according to a mutual distancebetween centres not lower than 1.5 times the diameter of the thread-likeelements themselves, in order to enable an appropriate rubberizingaction between the respectively adjacent threads.

The continuous strip-like element 2 a coming out of extruder 18 can beadvantageously guided, possibly through a first accumulator-compensatordevice 19 a, on a deposition apparatus the structure and operatingfeatures of which are described in more detail in the European PatentApplication No. 97830731.2 in the name of the same Applicant, contentsof which is considered as herein incorporated.

This deposition apparatus is suitable for sequentially cutting thecontinuous strip-like element 2 a for obtaining strip-like sections 13,14, 15, 16 of predetermined length.

Cutting of each strip-like section 13, 14, 15, 16 is immediatelyfollowed by deposition of same section onto the toroidal support 11,giving the strip-like section a U-shaped configuration around thecross-section outline of the toroidal support itself, so that in thestrip-like section 13, 14, 15 16 two side portions 13 a, 14 a, 15 a, 16a can be identified which extend radially towards the axis of thetoroidal support 11, at positions axially spaced apart from each other,as well as a crown portion 13 b, 14 b, 15 b, 16 b extending at aradially outer position between said side portions.

Due to the sticking quality of the raw elastomer material forming layer20 coating the thread-like elements 17, a steady adhesion of thestrip-like element 13, 14 to the surfaces of the toroidal support 11 isensured, even in the absence of liner 10 on the toroidal support itself.In more detail, the above described adhesion appears as soon as thestrip-like section 13, 14 comes into contact with the toroidal support11 at a radially outer region of its cross-section outline.

In addition to, or in place of the above described exploitation of thenatural sticking quality of the elastomer material, holding of one ormore of the strip-like sections 13, 14 on the toroidal support 11 can beobtained by carrying out a suction action produced through one or moresuitable holes arranged on said toroidal support.

The toroidal support 11 can be driven in angular rotation according to astep-by-step movement in synchronism with operation of said depositionapparatus, in such a manner that each cutting action of each strip-likesection 13, 14, 15, 16 is followed by deposition of same at a positioncircumferentially spaced apart from the previously laid down section 13,14, 15, 16.

In more detail, rotation of the toroidal drum 11 takes place accordingto an angular pitch to which a circumferential displacement equal to amultiple of the width of each strip-like section 13, 14, 15, 16 and morespecifically twice said width, corresponds.

It is to point out that to the aims of the present description the term“circumferential”, when not otherwise stated, refers to a circumferencelying in the equatorial plane X—X and close to the outer surface of thetoroidal support 11.

In accordance with the present invention, the above described operatingsequence is such that, by a first full revolution of the toroidalsupport around its own axis, deposition of a first series of strip-likesections 13, circumferentially distributed according to acircumferential pitch which is twice the width of each of them, iscaused. Therefore, as clearly viewed from FIG. 4, an empty space “S” isleft between one and the other of the sections belonging to the firstseries, which empty space, at least at the crown portions 13 b of saidsections, has the same width as sections themselves.

Preferably, deposition of the strip-like sections 13 belonging to thefirst series takes place in an inclined orientation relative to thecircumferential-extension direction of the toroidal support, preferablyat an angle included between 15° and 35°.

Adjustment of the deposition angle of the strip-like sections can beobtained for example by suitably orienting the geometric rotation axisof the drum relative to the deposition apparatus.

Manufacturing of a carcass structure 2 then goes on with the step ofapplying first primary portions 4 a of said inextensible annularstructures 4 close to each of the inner circumferential edges of thecarcass ply 3 being manufactured, for the purpose of obtaining thecarcass regions known as “beads”, which are particularly intended forensuring anchoring of the tire to a corresponding mounting rim.

Each of said first primary portions 4 a comprises at least one firstcircumferentially inextensible annular insert 21, substantially havingthe shape of a crown concentric with the geometric rotation axis of thetoroidal support 11 and located at a circumferentially inner positionagainst the end flaps exhibited by the strip-like sections 13 belongingto the first series.

The first annular insert 21 is preferably made up of at least oneelongated metal element wound up in several substantially concentriccoils 21 a. Coils 21 a can be defined either by a continuous spiral orby concentric rings formed of respective elongated elements.

Combined with the first annular insert 21 is a first filling body 22 ofelastomer material, preferably of the thermoplastic type, having ahardness included between 48° and 55° Shore D, measured at a temperatureof 23° C. and preferably having a radial extension higher than theradial extension of the first annular insert 21.

As shown in FIG. 5, accomplishment of each first primary portion 4 a canprovide, for example, that within a moulding cavity 23 defined in amould 23 a, 23 b the first inextensible annular insert 21 should beformed through deposition of at least one elongated element inconcentric coils 21 a which are disposed in mutual side by siderelationship according to circumferences of an increasingly growingdiameter around their geometric winding axis, corresponding to therotation axis of the finished tire.

This operation can be advantageously carried out by winding theelongated element in a helix-shaped forming seat arranged in a firstcheek 23 a of mould 23 a, 23 b which to this purpose can be driven inrotation around a geometric axis thereof.

Deposition of the elongated element can be advantageously preceded by arubberizing step in which the elongated element itself, preferably of ametal material, is coated with at least one layer of raw elastomermaterial that, in addition to ensure an excellent rubber-metal bond onthe elongated element itself, promotes adhesion of same for its steadyplacement in said helix-shaped seat.

In addition, at least the first cheek 23 a may be advantageouslyprovided to be made of a magnetic material or a material to beelectromagnetically activated, so as to suitably attract and retain theelongated element, thereby ensuring a steady positioning of coils 21 aas they are formed.

Then within the moulding cavity 23 the first filling body 22 is formed.Forming of said body can be conveniently carried out by interposing,between the first cheek 23 a carrying the first annular insert 21 andthe second cheek 23 b, at least one annular element of raw elastomermaterial of predetermined volume. This annular element can have anyconvenient conformation in cross-section, provided its volumecorresponds to the inner volume of the moulding cavity 23 when cheeks 23a, 23 b are moved close to each other in a closed condition of themould.

Once the annular element has been positioned between cheeks 23 a, 23 b,closing of the moulding cavity 23 is carried out by mutual approachingof said cheeks. Under this circumstance, the volume of the mouldingcavity 23 is reduced, so that the annular element of raw elastomermaterial is pressed and is subjected to deforming until it completelyfills the moulding cavity itself, thereby forming the first filling body22 that remains intimately joined to the first annular insert 21.

As an alternative solution to the above description, formation of thefilling body 22 can be carried out for example after mutuallyapproaching cheeks 23 a, 23 b, by filling the moulding cavity 23 withelastomer material introduced by injection, or by adopting any othermanner which may be convenient for a person skilled in the art.

By operating as above described, respective first primary portions 4 aof the annular reinforcing structures 4 are obtained, accomplishment ofwhich can advantageously take place close to the toroidal support 11, insuch a manner that said first primary portions, possibly with the aid ofappropriate handling devices, can be directly picked up from mould 23 a,23 b and laterally applied at axially opposite positions relative to theequatorial plane of the toroidal support, each of them with the firstannular insert 21 against the previously-arranged end flaps of sections13 belonging to the first series.

As an alternative solution to the preceding description, accomplishmentof the first primary portions 4 a can involve formation of the firstfilling body 22 separately from the first annular insert 21, andsubsequent union of the first filling body with the first annular insertpreviously applied to the end flaps of the strip-like sections 13 laiddown on the toroidal support 11.

In more detail, in accordance with a preferential embodiment, the firstannular insert 21 is preferably directly manufactured against the endflaps of the strip-like sections 13, coils 21 a being formed by windingup the thread-like element with the possible aid of rollers or othersuitable means acting against the surface of the toroidal support 11.

The sticking quality of the elastomer layer 20 coating the strip-likesections 13 belonging to the first series, as well as of the possibleliner 10 previously laid down on the drum itself ensure a steadypositioning of the individual coils 21 a being formed.

Subsequently, the first filling body 22 can be in turn directly formedagainst the first annular insert 21, by applying a continuous strip ofelastomer material coming out of an extruder placed close to the drum 11itself, for example. The continuous strip may have the definitiveconformation in section of the first filling body 22 already on itscoming out of the respective extruder. Alternatively, the continuousstrip shall have a reduced section compared with that of the fillingbody, and the latter will be obtained by application of the strip inseveral coils disposed in side by side and/or overlapping relationship,so as to define the first filling body 22 in its final configuration.

After application of the first primary portions 4 a of the annularreinforcing structures 4, formation of the first carcass ply 3 a iscompleted by deposition of the second series of strip-like sections 14obtained by cutting the continuous strip-like element 2 a to size, whichsections 14 are applied to the toroidal drum 11 in the same manner asdescribed for the strip-like sections 13 belonging to the first series.

As clearly viewed from FIG. 6, each section 14 belonging to the secondseries is laid down in a U-shaped conformation around the cross sectionoutline of the toroidal support 11, between two consecutive sections 13belonging to the first series and according to an orientation parallelto said sections 13. In more detail, each section 14 belonging to thesecond series has a respective crown portion 14 b circumferentiallyinterposed between the crown portions 13 a of sections 13 belonging tothe first series, to fill space “S” existing therebetween, as well as apair of side portions 14 a carrying the end flaps of the section itselfin superposed relationship with the respective first primary portions 4a of the annular reinforcing structures 4, at axially opposite positionsrelative to the end flaps of sections 13 belonging to the first series.

In other words, the first primary portion 4 a of each annularreinforcing structure 4, having a section outline substantially in theform of a triangle the vertex of which is turned away from the tireaxis, has an axially inner side turned towards the end flaps of thestrip-like sections 13 belonging to the first series, and an axiallyouter side turned towards the end flaps of sections 14 belonging to thesecond series.

In addition, the side portions 14 a of each section 14 belonging to thesecond series may be also provided to partly overlap the side portions13 a of two consecutive sections 13 belonging to the first series, eachat a stretch included between the radially outer edge of the respectiveprimary portion 4 a and the transition region between the side portionitself and the crown portion 13 b, 14 b.

Due to the mutual convergency between the contiguous side portions 13 a,14 a oriented radially of the geometric axis of the toroidal support 11,overlapping or covering of the side portions 13 a of sections 13belonging to the first series, i.e. the circumferential width of theoverlapping regions, progressively decreases starting from a maximumvalue, which can be detected close to the radially outer edge of thefirst primary portion 4 a of each annular reinforcing structure 4, untila null value at the transition region between the side portions 13 a, 14a and crown portions 13 b, 14 b.

After carrying out deposition of the strip-like sections 14 belonging tothe second series in the manner as above described, formation of thesecond carcass ply 3 b is started by laying down the third series ofstrip-like sections 15.

This deposition step can be performed in the same manner as alreadydescribed with reference to deposition of sections 13, 14 belonging tothe first and second series or in a similar manner.

In a convenient solution, the strip-like sections 15 belonging to thethird series are laid down in a crossed orientation relative to sections13 and 14 of the first and second series, preferably according to asymmetrically opposite angle relative to the last-mentioned sections,with reference to the circumferential-extension direction of carcassstructure 2.

Also the strip-like sections 15 belonging to the third series are laiddown in a U-shaped configuration around the cross section outline of thefirst carcass ply 3 a, and according to a circumferential pitchcorresponding to a multiple of their width, and preferably to twice saidwidth.

Then application of second primary portions 4 b of the annularreinforcing structures 4 to the end flaps of the strip-like sections 15belonging to the third series is carried out, at axially oppositepositions relative to the above mentioned first primary portions 4 a.

As viewed from the accompanying figures, each of the second primaryportions is preferably structured in the same manner as described withreference to the first primary portions 4 a.

In particular, each second primary section 4 b has a respective secondcircumferentially-inextensible annular insert 24 made up of at least onerespective elongated element disposed in concentric coils 24 a so as toform a crown disposed coaxially with the carcass structure 2 and closeto the inner circumferential edges of the carcass plies 3 a, 3 b.

Combined with the second annular insert 24, disposed against the endflaps of the strip-like sections 14, 15 belonging to the second andthird series, is a second filling body 25 of elastomer material, havingthe same conformation as the first filling body 22.

Accomplishment and application of the second annular insert 24 and thesecond filling body 25, as well as the second primary portion 4 b takenas a whole, can take place according to anyone of the previouslydescribed modalities, with reference to the first primary portion 4 a.

Formation of the second carcass ply 3 b is subsequently completed, bydeposition of the fourth series of strip-like sections 16 eachinterposed between two of the strip-like sections 15 belonging to thethird series and overlapping the second primary portions 4 b by theirend flaps, at an axially opposite position relative to the end flaps ofsections 14, 15 belonging to the second and third series, respectively.

When deposition of the fourth series of the strip-like sections 16 hasbeen completed, the second primary portion 4 b of each annularreinforcing structure, which too has the shape of a triangle in crosssection, has an axially inner side turned towards the end flaps of thesections belonging to the third series 15 and an axially outer sideturned towards the end flaps of the sections belonging to the fourthseries 16.

In accordance with a preferential solution of the invention, afterdeposition of the strip-like sections 16 belonging to the fourth serieshas been carried out, formation of the annular reinforcing structures 4at the beads is completed.

For the purpose, as shown in FIG. 9, for each of the annular reinforcingstructures 4 application of an additional portion 26 is provided againstthe end flaps of the strip-like sections 16 belonging to the fourthseries.

Preferably, each additional portion 26 is essentially made up of atleast one additional annular insert in the shape of a crown. Thisadditional annular insert 26 can be obtained by winding a respectiveelongated element for example, in concentric coils 26 a at a formingseat 27 arranged in an auxiliary matrix 28, in the same manner asdescribed with reference to formation of the first and second annularinserts 21, 24.

By axially moving matrix 28 towards the toroidal support 11, applicationof the additional annular insert 26 against the carcass structure 2 iscarried out.

Alternatively, said elongated element can be directly wound against thesecond carcass ply 3 b previously formed on the toroidal support 11, soas to create the second annular insert 26 directly in contact with thecarcass ply itself.

Following this operation, each of the end flaps of sections 16 belongingto the fourth series advantageously keeps an enclosed position betweenthe second primary portion 4 b and the addition portion 26 of therespective annular reinforcing structure 4.

In tires of the radial type, a belt structure 5 is usually applied tothe carcass structure 2.

This belt structure 5 can be manufactured in any manner convenient for aperson skilled in the art and, in the embodiment shown, it essentiallycomprises a first and a second belt strips 6 a, 6 b having cords with arespectively crossed orientation. Superposed on the belt strips is anauxiliary belt strip 7, for example obtained by winding of at least onecontinuous cord in substantially circumferential coils disposed axiallyin side by side relationship, around the belt strips themselves.

Then, the tread band 8 is applied to the belt structure 5, whereassidewalls 9 are applied to the side portions of the carcass structure 2,which elements are also obtained in any manner convenient for a personskilled in the art.

Examples of a belt structure, sidewalls and a tread band to beadvantageously adopted for completely manufacturing tire 1 on thetoroidal support 11 are described in the European Patent Application No.97830632.2 in the name of the same Applicant.

Tire 1 thus manufactured is now ready to be submitted, possibly afterremoval from support 11, to a vulcanization step that can be conductedin any known and conventional manner.

The present invention achieves important advantages.

In fact, the carcass structure in reference can be directly obtained ona toroidal support on which the whole tire can be advantageously formed.In this way, all problems connected with manufacturing, storage andmanagement of semifinished products, common to manufacturing processesof traditional conception, are eliminated.

As compared with the method described in document U.S. Pat. No.5,362,343 the manufacturing time for the carcass ply can be greatlyreduced, by virtue of the simultaneous deposition of as many thread-likeelements as they are contained in each strip-like section 13, 14 or inthe continuous strip-like element 2 a from which sections 13, 14 come.Employment of strip-like sections 13, 14 also dispenses with the needfor previously laying down liner 10 on the toroidal support 11. Theelastomer layer 20 employed in forming the continuous strip-like element2 a is in fact adapted by itself to ensure an efficient adhesion of sameto the toroidal support 11, thereby ensuring a steady positioning of theindividual sections 13, 14.

Accuracy in positioning of the strip-like sections 13, 14 andthread-like elements integrated thereinto is further improved by thefact that each strip-like section has an important structuralconsistency that makes it insensitive to vibrations or similaroscillation effects which can be transmitted by the depositionapparatus. In this connection it is to note that deposition ofindividual cords, as described in U.S. Pat. No. 5,362,343, may besomewhat problematic, exactly due to vibrations and/or oscillationsundergone by said cords during the deposition step.

Furthermore, simultaneous deposition of a plurality of thread-likeelements in accordance with the invention enables the depositionapparatus to be operated at slower rates than required when depositionof individual cords is concerned, which is a further advantage in termsof working accuracy without on the other hand impairing productivity.

Besides, deposition of strip-like sections directly crownwise to atoroidal support of an outline substantially identical with that of thefinished tire enables densities to be achieved that cannot be reached inthe art by known methods providing deposition of a carcass ply in theform of a cylindrical sleeve and subsequent shaping of same into atoroidal form, with consequent thinning of the carcass ply cordsdisposed crownwise to the finished tire.

In addition to the above, each strip-like section can be steadilyfastened to the toroidal support by a vacuum effect produced throughpossible suction ducts, which steady fastening by vacuum cannot beachieved by known processes carrying out deposition of individual cords.

The construction and structure conception of the subject tire,particularly with reference to its carcass structure 2, enablesimportant improvements to be achieved in terms of structural strength,above all close to the sidewalls and beads where a greater structuralstrength is usually required, as well as in terms of behaviour,especially in connection with the effects of the slip thrusts that occurwhen tires are run on bends, at the same time benefiting from alladvantages typically correlated with a single-ply carcass structure.

In particular, the construction features of the inextensible annularstructures 4 and the modalities according to which they are integratedin the carcass ply are such that they further increase the structuralstrength of tire 1 at the bead and sidewall regions.

In fact, the presence of the circumferentially inextensible annularinserts 21, 24, 26 intimately joined to the carcass plies 3 a, 3 boffers an excellent “link” with the thread-like elements 17 belonging tothe different series of strip-like sections 13, 14, 15, 16. Thus thecarcass structure 2 is further strengthened at the regions correspondingto the tire 1 beads without for the purpose requiring employment ofadditional strip-like inserts, usually called “flippers”, wound as aloop around the inextensible annular structures 4, to which on thecontrary resort is made in the known art.

As a matter of fact, due to the construction conception of the annularreinforcing structures 4, the tire beads are prevented from deforming,under the effects of slip thrusts, or from rotating around their restpoints against the respective security humps provided in the wheel rim.

In particular, it is to note that the presence of the first insert 21,the second insert 24 and the auxiliary insert 26, disposed in directcontact with the end flaps of the strip-like sections, efficientlyprevents the bead tendency to bend and rotate under the effect of theslip thrusts.

Under this point of view, the behaviour of the annular reinforcingstructure 4 is substantially similar to that of a reinforcing structureas described in the European patent application No. 97830731.2 in thename of the same Applicant, to which please refer for further details.It is also to note that the annular inserts 21, 24 and 26 furnish afurther structural protection of the tire at the beads.

The structural strength at the tire sidewalls, in particular withreference to torsional stresses induced in the acceleration and brakingsteps, is greatly increased, by virtue of the mutually-crossedarrangement of the strip-like sections 14, 15 belonging to the secondand third series respectively, which are disposed inside the annularreinforcing structures 4.

This aspect is particularly advantageous with reference tohigh-performance low-profile tires where the structural strength of thesidewalls is greatly critical, also due to the high torque values thatthe tire must be able to transmit.

What is claimed is:
 1. A method of manufacturing a carcass structure fora vehicle tire, comprising: preparing strip sections, each comprisinglongitudinal and parallel thread elements at least partly coated with atleast one layer of raw elastomer material; laying down a first series ofthe strip sections on a toroidal support, each of the strip sectionsextending in a substantially U-shaped conformation around across-sectional outline of the toroidal support and circumferentiallydistributed according to a circumferential pitch corresponding to amultiple of a width of the strip sections of the first series; applyingfirst primary portions of annular reinforcing structures against endflaps of the strip sections of the first series at axially-oppositepositions relative to an equatorial plane of the toroidal support;laying down on the toroidal support at least one second series of thestrip sections, each extending in a substantially U-shaped conformationaround the cross-sectional outline of the toroidal support between twoconsecutive strip sections of the first series, in order to define,together with the strip sections of the first series, a first carcassply, each of the strip sections of the at least one second seriescomprising end flaps overlapping respective first primary portions ofthe annular reinforcing structures at an axially-opposite positionrelative to the end flaps of the strip sections of the first series;laying down on the toroidal support a third series of the stripsections, each extending in a substantially U-shaped conformation aroundthe cross-sectional outline of the toroidal support andcircumferentially distributed according to a circumferential pitchcorresponding to a multiple of the width of the strip sections of thethird series; applying second primary portions of the annularreinforcing structures against end flaps of the strip sections of thethird series at axially-opposite positions relative to the first primaryportions; and laying down on the toroidal support at least one fourthseries of the strip sections, each extending in a substantially U-shapedconformation around the cross-sectional outline of the toroidal supportbetween two consecutive strip sections of the third series, in order todefine, together with the strip sections of the third series, a secondcarcass ply overlapping the first carcass ply, each of the stripsections of the at least one fourth series comprising end flapsoverlapping respective second primary portions of the annularreinforcing structures at an axially-opposite position relative to theend flaps of the strip sections of the third series.
 2. A method ofmanufacturing a vehicle tire, comprising: manufacturing a carcassstructure; applying a belt structure to the carcass structure at acircumferentially-outer position of the carcass structure;circumferentially superposing a tread band on the belt structure; andproviding sidewalls on opposite side portions of the carcass structure;wherein manufacturing the carcass structure comprises: preparing stripsections; laying down a first series of the strip sections on a toroidalsupport; applying first primary portions of annular reinforcingstructures against end flaps of the strip sections of the first seriesat axially-opposite positions relative to an equatorial plane of thetoroidal support; laying down on the toroidal support at least onesecond series of the strip sections; laying down on the toroidal supporta third series of the strip sections; applying second primary portionsof the annular reinforcing structures against end flaps of the stripsections of the third series at axially-opposite positions relative tothe first primary portions; and laying down on the toroidal support atleast one fourth series of the strip sections; wherein each stripsection comprises longitudinal and parallel thread elements at leastpartly coated with at least one layer of raw elastomer material, whereineach strip section of the first series extends in a substantiallyU-shaped conformation around a cross-sectional outline of the toroidalsupport, wherein each strip section of the first series iscircumferentially distributed according to a circumferential pitchcorresponding to a multiple of a width of the strip sections of thefirst series, wherein each strip section of the at least one secondseries extends in a substantially U-shaped conformation around thecross-sectional outline of the toroidal support between two consecutivestrip sections of the first series, in order to define, together withthe strip sections of the first series, a first carcass ply, whereineach strip section of the at least one second series comprises end flapsoverlapping respective first primary portions of the annular reinforcingstructures at an axially-opposite position relative to the end flaps ofthe strip sections of the first series, wherein each strip section ofthe third series extends in a substantially U-shaped conformation aroundthe cross-sectional outline of the toroidal support, wherein each stripsection of the third series is circumferentially distributed accordingto a circumferential pitch corresponding to a multiple of a width of thestrip sections of the third series, wherein each strip section of the atleast one fourth series extends in a substantially U-shaped conformationaround the cross-sectional outline of the toroidal support between twoconsecutive strip sections of the third series, in order to define,together with the strip sections of the third series, a second carcassply overlapping the first carcass ply, and wherein each strip section ofthe at least one fourth series comprises end flaps overlappingrespective second primary portions of the annular reinforcing structuresat an axially-opposite position relative to the end flaps of the stripsections of the third series.
 3. The method of claim 2, wherein thestrip sections of the first series and the at least one second seriesare laid down in a crossed orientation with respect to the stripsections of the third series and the at least one fourth series.
 4. Themethod of claim 3, wherein the strip sections of the first series andthe at least one second series are laid down in a first orientationinclined at an angle included between 15° and 35° relative to acircumferential-extension direction of the toroidal support, and whereinthe strip sections of the third series and the at least one fourthseries are laid down in a second orientation inclined at an angleincluded between 15° and 35° relative to the circumferential-extensiondirection of the toroidal support.
 5. The method of claim 2, furthercomprising applying additional portions of the annular reinforcingstructures against the end flaps of the strip sections of the at leastone fourth series, so that each end flap of the strip sections of the atleast one fourth series is enclosed between the second primary portionsand the additional portions of respective annular reinforcingstructures.
 6. The method of claim 2, wherein each of the strip sectionsis laid down so as to form two side portions, substantially extending ina direction of a geometric rotation axis of the toroidal support atmutually-spaced-apart positions in an axial direction, and a crownportion, extending at a radially-outer position between the sideportions, wherein the crown portions of the strip sections of the firstseries and the at least one second series are disposed consecutively inside-by-side relationship along a circumferential extension of thetoroidal support, and wherein the crown portions of the strip sectionsof the third series and the at least one fourth series are disposedconsecutively in side-by-side relationship along a circumferentialextension of the toroidal support.
 7. The method of claim 6, wherein theside portions of each strip section of the first series are each partlyoverlapped by a side portion of at least onecircumferentially-consecutive strip section of the at least one secondseries, between a radially-outer edge of the first primary portions ofthe annular reinforcing structures and a transition region from the sideportions of the strip sections of the at least one second series to thecrown portions of the strip sections of the at least one second series,and wherein the side portions of each strip section of the third seriesare each partly overlapped by a side portion of at least onecircumferentially-consecutive strip section of the at least one fourthseries, between a radially-outer edge of the second primary portions ofthe annular reinforcing structures and a transition region between theside portions of the strip sections of the at least one fourth seriesand the crown portions of the strip sections of the at least one fourthseries.
 8. The method of claim 6, wherein the side portions of the stripsections radially converge toward a geometric rotation axis of thetoroidal support.
 9. The method of claim 2, wherein accomplishment of atleast one of the first and second primary portions of each annularreinforcing structure comprises the steps of: laying down at least oneelongated element in concentric coils to form a firstcircumferentially-inextensible annular insert substantially in a form ofa crown; forming at least one filling body of elastomer material; andjoining the at least one filling body to the first annular insert. 10.The method of claim 9, wherein the at least one elongated element isdeposited directly against end flaps of at least one of the first andthird strip sections previously deposited on the toroidal support toform the first annular insert.
 11. The method of claim 9, wherein the atleast one filling body is formed by depositing a continuous strip ofelastomer material directly against the first annular insert.
 12. Themethod of claim 9, wherein the at least one elongated element is laiddown in a forming seat defined in a moulding cavity in which the atleast one filling body is subsequently formed, so that joining of the atleast one filling body to the first annular insert is carried outconcurrently with formation of the at least one filling body.
 13. Themethod of claim 9, wherein the joining step is carried out by applyingthe at least one filling body against the first annular insert.
 14. Themethod of claim 5, wherein formation of the additional portions of theannular reinforcing structures comprises the step of depositing at leastone elongated element in concentric coils to form an additionalcircumferentially-inextensible annular insert substantially in the formof a crown.
 15. The method of claim 14, wherein the at least oneelongated element is laid down directly against the strip sections ofthe at least one fourth series during the formation of the additionalportions.